The present application is related to and claims priority from Japanese Patent Application No. 00-106690, filed on Apr. 4, 2000.
The present invention relates to an optical disk device playing back information from an optical information recording medium. More specifically, the present invention relates to a method for playing back data in the same.
Conventionally, various systems have been known and put in use regarding optical disk devices. In these optical disk devices, optically recorded information is read and played back. Information is recorded on optical information recording media by forming recording marks on a disc-shaped optical recording medium using concave and convex pits, phase changes, or the like. Recent years have seen development and attention placed on optical recording media such as those known as DVDs that provide higher information recording density and allow large amounts of information to be recorded. Some optical disk devices that can read and playback or record/playback recorded information from these disks are already commercially available.
In this type optical recording medium (hereinafter referred to as optical disks) such as DVD, ECC (Error Correction Code) blocks serve as the smallest unit for recording data. An ECC blocks is formed from 16 sectors (or frames) of 2048 bytes, providing a total capacity of 32 kbytes. Error correction is performed on these ECC blocks to assure data reliability. There are two types of error correction. PI correction corrects individual sectors and PO correction corrects 16-sector blocks. Improved error correction performance is provided by using both types of error correction.
In high-density recording media such as DVDs, laser beams with shorter wavelength compared to those from conventional optical disk devices such as CDs is used for optical playback means in order to increase information recording density on the disc-shaped medium. Track pitch density is also increased. Thus, concave and convex formations known as land regions and groove regions are formed on the recording surface of the medium, and information is recorded in these regions. These land regions and groove regions are alternated every time around based on the tracking operation performed by the optical pickup, which serves as optical playback means.
Various types of high-density recording media have been proposed such as recording media from which recorded information can only be played back, recording media which can only record once, and recording media which can be recorded a plurality of times.
Playback of data from the high-density recording media described above can be easily affected by various playback conditions such as focus and tracking. Errors can occur even with the error correction described above, and it is necessary to handle these.
Furthermore, since the smallest recording unit is large, as in the ECC block, playing back data from these smallest recording units on a high-density recording medium can result in difficulties in finding optimal playback conditions. This can result in multiple playback retries and long data read times.
The object of the present invention is to overcome the problems described above and to provide an optical disk device and a method for playing back data for the same that plays back data at high speeds with a low number of playback retries even if an error occurs during a data read.
The present invention provides a method for playing back data from an optical information recording medium. A data recording block that includes a first error correction code series and a second error correction code series serves as the smallest recording unit. The second error correction code series in the smallest recording unit is divided into a plurality of groups and recorded. When playing back data from the smallest recording unit, a second error correction is performed on the second error correction code series. Information regarding whether or not the error correction was possible for each of the plurality of groups when performing the error correction is stored. A first error correction is performed on the first error correction code series. Data from the groups for which the second error correction was possible is stored if the first error correction is not possible. Data of the smallest recording unit from the optical information recording medium is played back again. Error correction is performed on the groups for which the second error correction was not possible, and the first error correction is performed.
In this invention, ECC blocks are used as the smallest recording unit, PO correction is used for the first error correction, and PI correction is used for the second error correction.
In this invention, before playing back data again from the optical information recording medium, at least one of the following conditions is changed: focusing conditions, tracking conditions, playback sync signal detection conditions, playback equalizer conditions, data slide conditions, and speed conditions.
Alternatively, in order to achieve the objects described above, the present invention provides an optical disk device playing back data from an optical information recording medium. A data recording block that includes a first error correction code series and a second error correction code series serves as the smallest recording unit. The second error correction code series in the smallest recording unit is divided into a plurality of groups and recorded. Means for playing back data plays back data from the smallest recording unit. Means for performing second error correction performs a second error correction on the second error correction code series. Means for performing first error correction performs a first error correction on the first error correction code series. Means for storing error evaluations stores whether or not error correction was possible for each of the plurality of groups. Means for controlling performs the following control operations. When playing back data, playback means plays back data from the smallest recording unit in the optical recording medium. Second error correcting means performs the second error correction on the playback data. Error evaluation storing means stores whether or not error correction was possible on the plurality of groups. First error correcting means performs the first error correction. If the error correction is not possible, data from the groups for which the second error correction was possible is stored. Data from the smallest recording unit on the optical information recording medium is played back again. Error correction is performed on groups for which the second error correction was not possible. The first error correction is performed.
In the optical disk device of the present invention, ECC blocks are used as the smallest recording unit, PO correction is used for the first error correction, and PI correction is used for the second error correction.
Also, the optical disk device of the present invention includes: means for controlling optical head focus; means for controlling tracking; means for detecting playback sync signals; means for setting up playback equalizer; means for setting up data slices; and means for controlling a disk rotation motor. Before playing back data from the optical recording medium again, controlling means changes control conditions for at least one means selected from the group consisting of focus controlling means, tracking controlling means, playback sync signal detecting means, playback equalizer settings controlling means, data slice settings controlling means, and disk rotation motor controlling means.